Bleach-fix processing

ABSTRACT

This application describes a bleach-fix process which comprises bleach-fixing photographic silver halide color material, after development of the silver image, in the presence of a watersoluble selenocyanate salt, selenourea, substituted selenourea or substituted selenouracil.

United States Patent Priorities David Gerald Alcock;

Enzo Plccotti, both 01 "ford. England 843,183

July 18, I969 Nov. 9, I971 lllord Limited Iliord. England July 24, 1968Great Britain Apr. 14, 1969, Great Britain, No. 18,934/69 BLEACH-FIXPROCESSING 9 Claims, No Drawings US. Cl

96/52. 96/60. 96/22 Int. Cl G036 5/32, G03c 7/00, G03c 5/26 [50] Fieldof Search 96/60, 60 BF,

Primary Examiner- Norman 0. Torchin Assn/an! Examiner-Mary F. KelleyAlmrney-Cushman, Darby & Cushman ABSTRACT: This application describes ableach-fix process which comprises bleach-fixing photographic silverhalide color material. after development of the silver image. in thepresence of a water-soluble selenocyanate salt. selenourea. substitutedselenourea or substituted selenouracil.

BLEACH-FIX PROCESSING This invention relates to color photography andmore particularly to the processing of photographic material comprisingsilver halide emulsion layers and adapted for processing to yield colorimages, (hereinafter referred to simply as "color photographicmaterial").

In the conventional processing of such color photographic material adevelopable silver salt image is developed with an aromatic primaryamino developing agent of the paraphenylene diamine type (a so-calledcolor developer") in the presence of a compound (a so-called colorcoupler") which will combine with the oxidation products of the colordeveloper to form an azomethine or quinone-imine dye. The dye is thusformed in situ with the developed silver image. SUbsequently the productmust be treated with a bleach bath and a fixing bath or a combinedbleach-fix bath thereby to remove silver and any residual silver halideor other silver salt, leaving in the product only the dye image.

The use of a combined bleach-fix bath is preferable because it resultsin a reduction of the processing time and of the processing equipmentrequired. Normally a bleach-fix bath comprises a mild oxidizing agentfor example a ferric-chelate complex, a cupric complex salt or a cobalt(Ill) complex together with a silver halide solvent or fixing agent forexample a water-soluble thiosulfate or a water-soluble thiocyanate.

Stable bleach-fix solutions comprising ferric chelate complexes andsodium thiosulfate may be obtained but because of the weak oxidizingpower of the ferric chelate complex such bleach-fix baths can only beused commercially for the processing of photographic materials with afairly low silver content.

lt is the object of the present invention to provide a bleachfix stepwhich can be used in the processing of color photographic material whichhave a relatively high-silver content, for example color negativematerial and color reversal material.

According to the present invention in a color development process forthe production of the colored image in exposed color silver halidephotographic material there is provided after the development step, thestep of treating the photographic material with an aqueous solution of ableach fix catalyst which is a water-soluble selenocyanate salt, aselenourea of the general formula I:

Re I

wherein R,, R and R, are hydrogen atoms or alkyl groups, at least one ofthem being a hydrogen atom or a selenouracil of the general formula ll:

wherein one of R, and R is a lower alkyl group and the other a hydrogenatom or both represent hydrogen atoms, and simultaneously orsubsequently treating the photographic material in a bleach-fix bathwhich comprises an aqueous solution comprising an oxidizing agent whichis either a ferric chelate or a diaquo-tetrammine-cobalt (lll) complex,and a silver halide solvent which is either a water-soluble thiosulfateor a watersoluble thiocyanate.

By lower alkyl group is meant an alkyl group which comprises from one tosix carbon atoms.

By ferric chelate complex is meant a coordination compound of the ferricion and a compound which comprises nitrogen and/or oxygen-containingcoordinating groups. The most important coordinating groups are amino,nitrogen heterocyclo, carboxyl and carbonyl groups.

The preferred ferric chelate complex for use in the bleachfix step ofthe present invention is a ferric ethylenediaminetetraacetic acidcomplex. It is to be understood that this compound may be used as suchin the preparation of a bleach-fix bath or it may be formed in situ in ableach-fix bath by ethylenediaminetetraacetic acid reacting with aferric salt e.g. ferric chloride. in the examples which follow theferric ethylenediaminetetraacetic acid complex has been formed in situ.

Other ferric chelate complexes which may be used in the presentinvention are for example pyridine-2:6-dicarboxylatoferrate (lll)complex, iminodiacetatoferrate (lll) complexand'nitrilo-triacetateferrate (lll) complex.

The preferred bleach-fix catalysts for use in the process of the presentinvention is a selenourea of the general formula III:

III

wherein R is a lower alkyl group.

The bleach-fix catalysts of use in the present invention are preferablyadded to the bleach-fix bath but they may be present during thebleach-fixing treatment adsorbed to or absorbed in the colorphotographic material. Thus the bleach-fix catalysts of use in thepresent invention, and in particular the bleach-fix catalysts of fonnulalll may be present in any treat ment bath or wash bath which is used inthe color development process between the development step and thebleachfix step. Exemplary of such baths are stop baths and stop-fixbaths. However in the case of selenocyanate these compounds cannot beused in an acid bath because they decompose yielding a highly toxic gas.

The bleach-fix catalysts cannot be present, however, in the developingsolution as they interfere with the development of the color material.For the same reason the bleach-fix catalysts of use in the presentinvention can not be present initially in the photographic material.

According to another embodiment of the present invention there isprovided a bleach-fix bath which comprises an aqueous solution of anoxidizing agent which is either a ferric chelate complex or adiaquo-tetrammine-cobalt (Ill) complex, a silver halide solvent which iseither a water-soluble thiosulfate or a watersoluble thiocyanate and ableach-fix catalyst which is a water-soluble selenocyanate salt, aselenourea of the formula I as hereinbefore set forth, or a selenouracilof fonnula ll as hereinbefore set forth.

It is preferred that the concentration of water-soluble selenocyanatesalt in the bleach-fix bath is from 0.l to 200 g. per liter of solutionand most preferably approximately 5 g. per liter of solution.

It is preferred that the concentration of selenourea of formula l or ofthe selenouracil of formula II present in the bleach-fix bath is from0.5 to 1.5 g. per liter of the solution and most preferably 0.1 g. perliter of solution.

It is preferred that in use the temperature of the bleach-fix bath isapproximately 24 C.

It is preferred that the concentration of the selenourea of formula I orof the selenouracil of formula ll present in a stop bath or a stop-fixbath or in a wash bath is from 0.5 mg. to 3.0 g. per liter of thesolution and most preferably 0.3 g. per liter of solution.

The following Examples with serve to illustrate the invention.

EXAMPLE I A negative tripack color material comprising a silver halideemulsion containing color couplers, was given a neutral wedge exposureand color processed, the processing sequence being as follows.

Color development 6 minutes Sodium metaborate 53.3 g. Sodium hydroxide2.0 g. Sodium sulfite anhydrous 3.9 g. Potassium bromide 0.70 g.Hydroxylamine sulfate 2.34 g. Sodium sulfate anhydrous 7.8 g.4-Amino-N-ethyl-N-(4-hydroxybutyl)- aniline sulfate 6.0 g. Water toliter Stop fix 4 minutes Sodium thiosulfate pentahydrate l7l.0 g. Sodiumacetate anhydrous 3|.4 g. Sodium sulfite anhydrous 4.3 g. Acetic acid(glacial) 35 ml. Potassium alum l7.0 g. Ammonium chloride 43.0 g. Water1 liter Wash 4 minutes Bleach-fix 25 minutes Disodium tctraboratedecahydrate l2.5 g. Boric acid 22.5 g. Sodium hydroxide 10.0 g.Ethylenediaminetetraacetic acid 16.2 g. Disodium salt ofethylenediaminetetraacetic acid dihydrate 3.5 g. Ferric chloride (60%WIV soln.) l mlv Sodium thiosulfate pentahydrate 95.0 g. Sodium sulfiteanhydrous 4.0 g. Water to 1 liter Wash 4 minutes Conditioner 4 minutesDisodium salt of ethylenediaminetetraacetic acid dihydrate 0.50 g.Sodium carbonate anhydrous 4.5 g. Formaldehyde (40% W/V loln.) l0 ml.Lissapol (8% soln.) l.7 ml. Water to 1 liter Walit 4 minutes Dry Theprocessed material was bleached in the low-exposure areas, butunsatisfactorily bleached in the parts at high-exposure.

A sample of the same photographic material was instead satisfactorilyprocessed by using the same processing sequence, but bleach-fixing itfor only 6 minutes, when 300 mg. of selenourea were added to thestop-fix bath described above.

EXAMPLE 2.

A color negative tripack as in example I, was given a neutral wedgeexposure and processed, the processing sequence being as in example 1,except for the stop-fix stage which was carried out in this example bytreating the material for 4 minutes in the following stop-fix bath.

Sodium thiosulfate pentahydrate |7t.0 g. Sodium acetate anhydrous 3L4 g.Sodium sulfate anhydrous 4.3 g. Acetic acid (glacial) 35 ml. Potassiumulum l7.0 g. Ammonium chloride 43.0 g. N-methyl-selenourea 300 mg. Waterto l liter The sample was found to be satisfactorily processed.

EXAMPLE 3.

A color negative tripack material as in example i, was given a neutralwedge exposure and processed, the processing sequence being as inexample 1, except for the stop-fix stage which was carried out bytreating the material for 6 minutes in a stop-fix bath of the followingcomposition.

Sodium thiosulfatc pentuhydratc l7l.0 g. Sodium acetate anhydrous 31.4g. Sodium sulfite anhydrous 4.3 g. Acetic acid (glacial) 35 ml.Potassium alum 17.0 g. Ammonium chloride 43.0 g. N,N-dimethyl-selenourea200 mg. Water to l liter The bleach-fixing time was 9 minutes and thesample was found to be satisfactorily processed.

EXAMPLE 4.

The tests described in the examples 1, 2 and 3 were re; peated, but the4 minutes wash between the stop-fix and the bleach-fix stage wasomitted.

The neutral wedge exposed photographic material was again satisfactorilyprocessed.

EXAMPLE 5.

EXAMPLE 6.

A color negative tripack as in example I was given a neutral wedgeexposure and satisfactorily processed by using a processing sequencesimilar to that described in example i, except that instead of thestop-fix bath a stop bath of the following composition was used.

Sodium acctate 9.0 g, Acetic acid (glacial) 5.2 ml. Sodium metalsulfite5.0 g. Selenourea 300 mg. Water to 1 liter The bleach-fix bath used inthis test has a composition similar to that of the bleach-fix bathdescribed in example 1, except that its sodium thiosulfate pentahydratecontent was raised to g.

Thebleach-fixing time was 6 minutes.

EXAMPLE 7.

A sample of the same photographic material as used in example l wasgiven a neutral wedge exposure and color processed using the sameprocessing sequence and processing 5 solutions as set forth in example Iexcept that 100 mg. of selenourea were present in the bleachix bath. Thebleach-fix time required was only 6 minutes and the material was foundto be satisfactorily bleached in the high-exposure areas.

EXAMPLE 8.

A color negative tripack material as in example I, was given a neutralwedge exposure and satisfactorily processed, the processing sequencebeing as in example I except for the bleach-fix stage, which was carriedout by treating the material for 8 minutes in the following bath.

a neutral wedge exposure and satisfactorily processed, the processingsequence being as in example l, except for the bleach fix stage whichwas carried out for 6 minutes in a bath having the followingcomposition.

Bleach-Fix Disodium tetraborate decahydrate 12.5 g. 45 Boric acid 22.5g.

Sodium hydroxide 100 g. Ethylenediaminetetraacetic acid 16.2 g.

Disodium salt of ethylenediaminetetraacetic acid dihydrate 3.5 g.

Ferric chloride (60% W/V soln.) l5 ml.

Sodium thiosulfatec pentahydrate 95.0 g. Sodium sulfite anhydrous 4.0 g.Potassium selenocyanate 5.0 g. Water to 1 liter pH 7.l

55 EXAMPLE 10.

Bleach-Fix 5 Diaquo-tetrummine cohalt (Ill) sulfate monohydrute 30.0 g.

Sodium thiosulphate pentahydrute l40.0 g.

selenourea 360 mg.

Water to l liter The same negative material was largely unbleached whenprocessed for the same time in a similar bleach fix bath but from whichthe selenourea had been omitted. 7

Although the examples given are based on the results obtained for atypical color negative material, similar improvements are obtained whencolor reversal material is bleachfixed with the exemplifiedcompositions.

The pHs of the solutions quoted are not a limiting factor for thecatalytic activity of the compounds disclosed, although solubleselenocyanates are unstable in acid solutions and tend to decompose withevolution of toxic gases.

We claim as our invention:

1. In a color development process for the production of a colored imagein exposed color silver halide photographic material. after thedevelopment step, the step of treating the photographic material with anaqueous solution ofa bleach-fix catalyst which is a water-solubleselenocyanate salt. a selenourea of the general formula:

It- .40 ll;

wherein R,, R and R are hydrogen atoms or alkyl groups, at least one ofthem being a hydrogen atom or a selenouracil of the general formula:

50 IT; N H

l ('r: (j r R5 (I) wherein one of R and R is a lower alkyl group and theother a hydrogen atom or both represent hydrogen atoms, andsimultaneously or subsequently treating the photographic material in ableach-fix bath which comprises an aqueous solution comprising anoxidizing agent which is either a ferric chelate or adiaquo-tetrammine-cobalt (lll) complex, and a silver halide solventwhich is either a water-soluble thiosulfate or a watersolublethiocyanate.

2. A process according to claim I wherein the bleach-fix catalyst ispresent in the bleach-fix bath.

3. A process according to claim 1 wherein the bleach-fix catalyst ispresent in a stop bath or stop-fix bath which is used to treat thephotographic material after development and prior to the bleach-fixstep.

4. A process according to claim 1 wherein the bleach-fix catalyst ispresent in a wash bath wherein the photographic material is washed afterdevelopment and prior to the bleachfix step.

5. A process according to claim 1 wherein the bleach-fix catalyst is aselenourea of the general formula:

ll R1 N(1--N II ll So it wherein R,, R, and R are hydrogen atoms oralkyl groups, at least one of them being a hydrogen atom or aselenouracil of the general formula:

wherein one of R, and R, is a lower alkyl group and the other a hydrogenatom or both represent hydrogen atoms.

7. A bleach-fix bath according to claim 6 wherein the bleach-fixcatalyst is a selenourea of the general formula:

wherein R, is a lower alkyl group.

8. A bleach-fix bath according to claim 6 wherein the con- [0 centrationof water-soluble selenocyanate salt therein is from 0.1 to 200 g. perliter of solution.

2. A process according to claim 1 wherein the bleach-fix catalyst ispresent in the bleach-fix bath.
 3. A process according to claim 1wherein the bleach-fix catalyst is present in a stop bath or stop-fixbath which is used to treat the photographic material after developmenTand prior to the bleach-fix step.
 4. A process according to claim 1wherein the bleach-fix catalyst is present in a wash bath wherein thephotographic material is washed after development and prior to thebleach-fix step.
 5. A process according to claim 1 wherein thebleach-fix catalyst is a selenourea of the general formula:
 6. Ableach-fix bath which comprises an aqueous solution of an oxidizingagent which is either a ferric chelate complex or adiaquo-tetrammine-cobalt (III) complex, a silver halide solvent which iseither a water soluble thiosulfate or a water-soluble thiocyanate and ableach-fix catalyst which is a water-soluble selenocyanate salt, aselenourea of the general formula:
 7. A bleach-fix bath according toclaim 6 wherein the bleach-fix catalyst is a selenourea of the generalformula:
 8. A bleach-fix bath according to claim 6 wherein theconcentration of water-soluble selenocyanate salt therein is from 0.1 to200 g. per liter of solution.
 9. A bleach-fix bath according to claim 6wherein the concentration of selenourea therein of the formula set forthin claim 6 or of selenouracil therein of the formula set forth in claim6 is from 0.5 mg. to 1.5 g. per liter of the solution.